1. Field of the Invention
This invention relates generally to systems and method for reading data from and writing data to data storage medium by employing the magnetic or optical recording technology. More particularly, this invention is related to a data card provided with at least one full circle data track among a group of data arc segments for card position alignment and signal amplitude calibration.
2. Description of the Prior Art
For a data card formed with multiple data arc segments, there is a need to determine the central axis of the data card to precisely position the data card for reading and writing data. As the data card has multiple arc segments, a more complex algorithm must be applied using a set of data obtained by reading data from multiple arc segments for the purpose of determining a central axis. The process is less efficient and may be time consuming thus preventing the operations of reading data from or writing data to the data card in a timely manner. In addition to the need to determine the central axis of the data card, it is also required to calibrate the data signals read from the data arcs because there are variations between different cards. For such calibration, an average-amplitude of the data signals as a magnetic or optical pickup head scan over the data arcs must be calculated. The average signal amplitude determined from measurements of multiple data points are generally required for such determination. Again, for a data card that has multiple data arcs, such calibration process may required data signals from multiple data arcs and thus would be less efficient and taking up longer times and slowing down the initialization of data reading and writing operations. Due to these reasons, less efficient operation and slower initialization may often be encountered when regular data card formed with multiple parallel data arcs are implemented.
The rotational head data recording and retrieving system as that disclosed in a co-pending Patent Application is implemented to resolve the difficulties of the conventional technology. Specifically, in conventional data storage systems, the reading and writing of data are performed on concentric circular data tracks. The concentric data track configuration often presents a problem that the data-bit density varies between the outer tracks and the inner tracks. The variable bit density in data storage is due to a geometrical factor that the outer data tracks are much longer in length than the inner tracks. A common practice is to form the inner tracks with a capacity to store the data bit at a higher bit density. A more complicate servo control system implemented with more complex signal-processing algorithms is required due to the variations of data storage density between different data tracks. Additionally, by varying the data storage density from the inner tracks toward the outside tracks, the data transfer rate is also changed in accessing data from the inner tracks then outside tracks. Such variation may also cause difficulties and complications in processing the data. Higher error rates may incur due to these variations between the inner tracks and the outer tracks.
There have been designs using pickup head with oscillating arm to prescribe multiple parallel data arcs at a flat data media and a constant data recording density for easier data access arrangement. There are also designs to use single or multiple rotating head pairs to prescribe multiple data arc segments on a circular track and/or on such multiple parallel track arrangements. All such designs required either pickup head with oscillating arm or head pairs configuration. All prior art designs also require that the flat media to be statically positioned to signal pickup heads once the flat media is engaged or inserted to the device.
An invention implemented with a rotational-head for data recording and retrieving as that disclosed in a co-pending Patent Application is able to resolve the above described difficulties of uneven data storage densities. However, the inefficiency and complexities of the operations to position the card and to calibrate the signal amplitude still present as technical difficulties to those of ordinary skill in the art yet to be resolved.
Therefore, a need still exists for an improved data-card operated with new configuration and method to overcome the technical difficulties as described above. Specifically, the storage card drive system shall provide a uniform density for data storage. Also, the data card should also provide a data tack configuration to conveniently determine a central axis of the data card and to measure the average signal amplitude for signal calibration. Furthermore, it would be desirable to keep the system portable and be provided with several standardized sizes for processing standardized data-storage cards.